Method and apparatus for dosing two types of molding sand into the molding box of a foundry mold

ABSTRACT

An apparatus for, and method of dosing two types of molding sand into a molding box of a foundry mold disposed beneath an intermediate container placed between a respective discharge device for each type of molding sand and the molding box. A relative movement occurs between at least one of the discharge devices and the intermediate container in order to continuously deposit a layer of a first type of molding sand into and substantially throughout the entire length of the intermediate container and with a width substantially corresponding to the width of the intermediate container. Then with a shift in phase there is simultaneously or during a further relative movement between the intermediate container and the discharge device continuously deposited into the intermediate container a layer of the second type of molding sand substantially over the entire length of the first layer of molding sand and with a width substantially corresponding to that of the intermediate container. The intermediate container is then brought into alignment with a filling frame placed upon the molding box and thereafter the contents of the intermediate container are emptied.

United States Patent [72] inventors Erwin Buhrer Breitenaustrtme 164;

Emil Maui-er, both of Schafihausen, Switzerland [21] Appl. No. 743,399

[22] Filed July 9, 1968 [45] Patented Aug. 24, 1971 {73] Assignee said Buhrer, by said Maurer [32] Priority Aug. 16, 1967 [33] Switzerland [54] METHOD AND APPARATUS FOR DOSING TWO TYPES OF MOLDING SAND INTO THE MOLDING 3,326,248 6/1967 Morgan 141/232 X FOREIGN PATENTS 774,305 12/1967 Canada 141/105 Primary Examiner-Laverne D. Geiger Assistant ExaminerEdward .l. Earls Attorney-Werner W. Kleeman ABSTRACT: An apparatus for, and method of dosing two types of molding sand into a molding box of a foundry mold disposed beneath an intermediate container placed between a respective discharge device for each type of molding sand and the molding box. A relative movement occurs between at least one of the discharge devices and the intermediate container in order to continuously deposit a layer of a first type of molding sand into and substantially throughout the entire length of the intermediate container and with a width substantially corresponding to the width of the intermediate container. Then with a shift in phase there is simultaneously or during a further relative movement between the intermediate container and the discharge device continuously deposited into the intermediate container a layer of the second type of molding sand substantially over the entire length of the first layer of molding sand and with a width substantially corresponding to that of the intermediate container. The intermediate container is then brought into alignment with a filling frame placed upon the molding box and thereafter the contents of the intermediate container are emptied.

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Emil. H0 MRQB ATTORNEY! 'ua'r uon ANDAPPARATUS roabosmc Two TYPES BACKGRQUND orrriamvau non The present inventioncrelates to an improved method of,

.and apparatus for, dosing two types of molding sand into a molding box or flask of a foundry mold while using two sand silos with associated discharge devices and an intermediate container arranged beneath the discharge devices. The floor of the intermediate container is formed by a louver or shutter closure, and further there is provided a filling frame arranged beneaththe intermediate container and which can be inserted upon the molding box to be filled.

It is known to the skilled foundryman that molding sand which should form a faultless, edge-free or smooth negative of a pattern must possess a minimum plastic form'ability. This minimum plastic formabilityis obtained by admixing a certain minimum quantity of bendable clay to the molding sand and by adding such a quantity of water thereto that, afie r mixing, it possesses the plastic condition required for carrying out the molding operation. This properly prepared molding sand referred to in the foundry as facing'sand enablesamold-which has been produced therefrom to be faultlesly removed or lifted from the pattern, without the mold edges crumbling or breaking off and without a tearing away of mold conglomerates. This minimum formability which the molding sand should poses for the above-explained reasons is, however, also necessary, in order to be able to. deposit cores withoutthe tearing away or breaking off of the edges of the sand.

If a mold is producedexclusively with such type molding sand,.generally referred toas uniform sand, then especially withlargermolds whicharenot-equippedwith any mold crossbars, thereis' a tendency towardsisettling or packingand too great aninaccuracy of the-casting. Additionally, it has been found thatiuniform molding sand which-is situated in the lower uniform sand, thenit is possible to mix'and knead a given total facing sand'and backing sand are employed instead of I quantity of molding sand with much less cost and less expenditure in equipment, since only the proportion of facing sand requires a longer and more intensive conditioningor preparation, whereas the proportion of backing sand need not be conditioned as intensively and much less time is required.

If there is used uniform sand, large quantities of sand lumps or nodules appear when emptying the mold. These sand lumps which are quite disturbing during operation, on the other hand, only appear to. such small'degree' that they are not disturbing when emptying a mold produced from facing sand and backing sand.

It is known to the art initially fill into an intermediate container a predetermined layer or stratum of facing sandand by carrying out a suitable changeover to then fill a predetermined layer of backing or packing sand. This filling technique possesses the drawback that it already precompresses the filled facing sand and discharge-from the feed silozand during filling ofthe molding box or flask located therebeneath, because the facing sand which tends to form bridges is discharged at certain locations at a later time from the intermediate container than the narrow parts of the pattern will only beinsufficiently compacted, whereas such sand which is located over the higher parts of the pattern, on the otherhand, is compacted much too hard. The explanation for these occurrences is that plastic molding sand-prepared for molding, is also extensively elastically deformable and, thus, when lifting the mold from the pattern it elastically relieves or expands, and that this molding sand requires a large amount'of compaction workwhich cannot be furnished for the lower parts of the pattern.

(0n the other hand, if a mold is produced only at the region of the pattern and with not too great a layer thickness from the previously mentioned plastic molding sand (facing sand) and if the remaining portion of the mold filled with a drier mold ingsand (backing or packing sand) containing lessclay, then it is alsopossible to produce quite accuratelyandwithoutsuch settling of the sand a larger mold without using ,crossbars. This is so because a molding sand which is dry and contains less clay is less elastically deformable, in other words, produces much more rigid molds. Since thedrier backing sand containing less clay requires much less compacting work, the parts of i the mold which are located at the lower portions of the pattern are automatically compacted more intensely than .when using a uniform sand. I

An initial reason for-employing two different molding sands, specifically facing sand and backing sand instead of uniform sand, for the production of a mold is that there can be'obtained a much greater-mold accuracy, uniform compaction and more stablemolds. When producing nodular iron or gray cast iron this is of particular importance, since during solidification there occur changes in volume which require a particularly stable mold.

Additionally, it has been found that the consumption of clay and coal dust can be reduced when .using facing sand and backing sand instead of unifonn sand.

backing sand located, thereadjacent and thereabove. Consequently, certain locations or portions of the pattern are covered with the nonplastic backing sand and therefore the thus produced molds become rejects. Furthermore, this technique cannot be employed to vary the height of the layer or the total prefilled quantity. Furthermore, it'is generally only suitable for small-size'moldsi for large. molds,.it'is unusable.

A further supply or feed apparatus is known which is espe cially provided for larger molds. Such embodies a stationary feed container for facing sand which is disposed beneath a facing sand silo equipped with a bar grate. The bar grate which isplaced into horizontal movement serves to discharge facing sand into the stationary feed container. In similar fashion, a further stationary feed container disposed beneath a backing sand silo is prefilled with backing sand. 'An intermediate container whose spatial position can be changed is now placed beneath the stationary feed container for the facing sand,

whereafter-facing sand is emptied out of "such feed container by means of a louver-or shutter closure into the intermediate I container.. After the intermediate containeris displaced beneath the feed container for the backing sand, backing sand is emptied out of this feed container in the same manner into the intermediate container which l ias been prefilled with facing sand. The quantity of moldingsand per unit time which can be supplied or distributed byv such' apparatus is considerably dependent upon the properties of the molding sand being handled at the moment. It is additionally dependent upon its position in the feed cross section since along the wall and especially in the corners of a silo the'distributed or sup- SUMMARY OF THE INVENTION Accordingly, it is a primary object of the present invention to make full use of the advantages which are obtained when using two types of sand without having to, contend with the above-mentioned drawbacks and difficulties.

by using a slidelike closure at silos to ments of apparatus mechanism 10.

FIG. I illustrates the beginning of an operating cycle, the intermediate container a and the discharge device 3 moving,

Another, more specific object of the present invention relates to an improved method of, and apparatus for dosing two types ofmolding sand into the molding box or flask of a foundry mold in a manner which overcomes the aforementioned drawbacks.

Y A further significant object of the present invention relates to an improved method of reliably and economically preparing molding'boxes or flasks containing two different types of molding sand.

Yet a further noteworthy object of the present invention pertains .to an improved apparatus for filling molding boxes or the like with two types of molding sand, such apparatus being relatively simple in construction, extremely reliable in operation, quite easy to use, and capable of producing molding boxes which have been properly filled with two types of molding sand.

Now, in order to implement these and still further objects of p the invention, which will become more readily apparent as the description proceeds, the inventive technique for dosing two I types of molding sand into a molding box of a foundry mold relies upon the features 6f moving an intermediate container and/or the discharge devices relative to one another. Thus, the molding sand removed from a first silo is continuously distributed over the entire length of the intermediate container with a width corresponding to the width of such intermediate container, and with a shift in phase simultaneously or during a further relative movement between the intermediate container and the discharge device distributing molding sand removed from. the second silo continuously over the entire length of the first layer of molding sand with a width corresponding to that of the intermediate container. Then the intermediate container is aligned with the filling frame placed upon the molding box, and thereafter the shutter-type closure of the intermediate container is opened.

. I BRIEF DESCRIPTION OF THE DRAWINGS The invention will be betterunderstood, and objects other" than those set forth above, will become apparent, when consideration is given to the following detailed description thereof. Suchdescription makes reference to the annexed drawings depicting a number of different exemplary embodifor practicing the inventive method, and

wherein:

FIGS. '1 to 4 schematically depict different intermediate positions during the operation of a first embodiment of inventive apparatus for dosing two types of molding sand into the molding box of a-foundry-mold;

FIG. 5 schematically illustrates an arrangement for closing the discharged quantity of sand from both silos; and

FIGS. 6 to 8 schematically depict different intermediate positions during the operation of a further exemplary embodiment of inventive apparatus for closing two types of molding sand into a molding box of a foundry mold.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Describing now the drawings, in FIGS. 1 to 4, inclusive, there are illustrated different intermediate operational positions'of a first embodiment of inventive apparatus for dosing two .types of molding sand into a molding box 9 of a foundry mold. This exemplary embodiment of apparatus incorporates two sand silos l and 2, each of which has operably associated therewith a suitable discharge device 3 and 4, respectively, here shown in the form of endless conveyor means. An intermediate container or receptacle 5, the spatial position of which can be varied, is arranged beneath the discharge devices 3 and 4, as shown. The floor or bottom of this intermediate container 5 is formed by a louveror shutter closure relative to one another. In so doing, the facing sand which is received from the silo l is continuously distributed over the Continuing, it will further be, understood that in order is reduce the fall height of thefacing sand delivered from the i conveyor band 3 intothe intermediate container 5, and to thereby prevent an undesired precompacting of this facing sand, there is advantageously provided a suitable slide plate or sheet 6 which extends from thedischarge end of the, conveyor band 3, the intermediate container 5 is displaced with}: uniform velocity or speed from the position of FIG. 1 towards the left until it has'reached the terminal position depicted in FIG. 2. As a result, a layer of loose facing sand of uniform height covers the entirefloor of the intermediate container 5. During this sand discharge operation, the slide' plate 6 does note change its position with respect to the conveyor band 3.

- Now, after the conveyor band 3 has reached the terminal position depicted in FIG. 2, this conveyor band 3 is stopped. Now, the conveyor band 4 which is associated with the silo 2 is placed into operation and the intermediate container 5 is displaced towards the right, as best shown by referring to FIG. 3, with a uniform velocity. In order to obtain a uniform and loose covering of the layer of facing sand which is already deposited in the intermediate container 5, the slide plate .6 is now placed in substantially vertical position, as shown, and completed by the addition of an impact plate 23, which also simultaneously prevents the packing or backing sand which is strewn over the facing sand from falling out of the intermediate container 5 when the latter reaches its terminal position, as shown in FIG. 4, through the open end wall 50 of this intermediatecontainer 5. It will be recognized by inspecting FIG. 1 that this end wall 50 is downwardly open up to a height a in order to allow entry of the slideplate 6. I I In the terminal position of the intermediate container 5, depictedin FIG. 4, this container is already disposed over the filling frame 8 which, in turn, has been placed upon a moulding box or flask 9. After opening the shutter closure mechanism 10 both of the superimposed layers of molding sand simultaneously drop out of the intermediate container 5 into the molding box 9.

Due to the loose filling of both layers of m ou lding sarid,.in.

would not fall simultaneously over the entire surface into the 1 molding box 9.

Now, for the purpose-of closing the discharged quantities. out of both silos l and 2, it is possible, as shown in FIG. 5, to provide these silos l and 2 with a respective discharge flap member 12 and 13, respectively, operatively connected with one another through the agency of a pivotal arm member 11. This pivotal arm member 11 is thus advantageously pivotablev about a horizontally extending shaft member 14..which is disposed substantially centrally between the discharge flaps or slides 12 and 13, and which is pivotable in the direction of the arrows 15. Furthermore, the shaft member 14, in turn, is mounted to be vertically displaceable in a vertical plane, in the direction of the arrows 16. By appropriately rocking or pivoting the pivotable arm member 11 in the direction of the arrows 15, it is possible to open or close the flaps or slide members 12 and 13. Consequently, it is possiblev to alter the proportion of facing sand and packing sand while retaining a constant total quantity of sand. Owing to the vertical displace-. ment of the shaft member 14, it, is possibletovary the total quantity of facing sand and packing sand. The shaking or reciprocating trough means 17, associated with each silo Land.

2, is placed into oscillation by means of the associated vibrator 18.

In order to enhance the dropping out of the molding sand located in the intermediate container 5, the latter can be conically tapered at least at the lower region thereof, generally designated by reference character 51, which is to be filled with the facing sand.

FIGS. 6 to 8, inclusive, schematically depict a further exemplary embodiment of inventive apparatus which, insofar as its structure is concerned, varies only to a slight extent from the inventive apparatus structure illustrated and described in connection with FIGS. 1 to 4. However, this embodiment of apparatus is operated partially different than the initial embodiment previously discussed.

In the embodiment of apparatus depicted in FIGS. 6 to 8, the slide plate 6, the impact plate 22 and the guide plate 7 are fixedly arranged with respect to one another and with respect to both of the discharge devices 3 and 4, again shown by way of example as conveyor band means. FIG. 6 illustrates the beginning of an operating cycle, wherein the intermediate I container 5 is located at the left-hand position of FIG. 6 from which it is displaced towards the right thereof with simultaneous discharge of facing sand from the conveyor band 3, as shown. The guide plate 7 extends for such a degree down into the intermediate container 5 towards the shutter closure mechanism 10 that it approximately contacts the upwardly directed surface of the previously deposited layer of facing sand.

After a predetermined displacement of the intermediate container 5, the conveyor band 4 begins to simultaneously discharge the packing or backing sand out of the silo 2 onto the layer of facing sand which is already deposited in the intermediate container 5. The guide plate 7 prevents the backing sand from depositing over the portion of the shutter closure mechanism 10 which has not yet been covered with facing sand. The discharge of facing sand by means of the conveyor band 3 is interrupted ata predetermined spacing of the intermediate container 5 prior to its having reached its terminal position. Shortly prior to reaching the terminal position of the intermediate container 5 the discharge of backing or packing sand by means of the conveyor band 4 is also interrupted.

Now, in FIG. 8, there is depicted the terminal position of the intermediate container 5. It will be recognized that this intermediate container 5 has now been filled with both layers of molding sand and is disposed above or in alignment with the filling frame 8, the latter having been placed upon a molding box or flask 9, as shown. In this position, the guide plate or beneath said discharge devices, and with a filling frame which can be placed upon the molding box arranged beneath the intermediate container, the improvement comprising carrying out a relative movement between the discharge devices and the intermediate container while continuously depositing a layer of a first type of molding sand delivered from one of said sand silos until, by reason of said relative movement, said first type of molding sand has been deposited throughout the entire length of the intermediate container and with a width substantially corresponding to the width of the intermediate container, controlling the movement of said first type of molding sand from said one silo into said intermediate container to influence the formation of said first layer of sand within said intermediate container, depositing a second layer of molding sand received from the second sand silo continuously onto and over the entire length of the first layer of molding sand and with a width which substantially corresponds to that of the intermediate container while carrying out a relative movement between the discharge devices and the intermediate container, then bringing the intermediate container into overlying relationship with respect to the filling frame which has been placed upon'the molding box, thereafter opening the shutter closure mechanism of the intermediate container, and thereby conjointly and simultaneously depositing both said first and second layers of molding sand from said intermediate container into the molding box.

2. A method of dosing two types of molding sand into a molding box as defined in claim 1, including the steps of displacing in a first at least approximately linear direction of displacement the intermediate container and the discharge devices relative to one another during removal of molding sheet 7 also prevents the packing sand which has been strewn over the facing sand from dropping out of the open end wall of the intermediate container 5, this end wall 50 being downwardly open to a height a for the purpose of permitting entry of the slide sheet 6. Additionally, it will be observed that it is possible to provide a funnel means 20, for instance formed by elastic side walls 52 which can be rolled up. This funnel means 20 is disposed between the filling frame 8 and the intermediate container 5, and the elastic sidewalls 52 thereof automatically roll up upon associated roller means 21 when lifting the filling frame 8.

Finally, it is mentioned that the speed of delivery of both conveyor bands 3 and 4 can be individually or conjointly regulated, as desired, by appropriately controlling the relevant conveyor speed of travel, for instance. Also, by way of example, a schematically depicted suitable drive means D can be operably associated with the intermediate container 5, for instance as shown in FIG. 1, in order to displace such container back and forth through a substantially linear path of travel.

It should be apparent from the foregoing detailed description, that the objects set forth at the outset to the specification have been successfully achieved.

ACCORDINGLY, we claim:

1. In a method of dosing two difierent types of molding sand irito a molding box of a foundry mold while using two sand silos with associated discharge devices and an intermediate container, the floor of which is formed by a shutter closure mechanism, said intermediate container being arranged sand from said one silo, and during removal of molding sand from the second silo carrying out a relative movement between the intermediate container and the discharge devices in a substantially linear direction which is opposite to the first direction of displacement.

3. A method of dosing two types of molding sand into a molding box as defined in claim 1, further including the step of regulating the feed velocity of both discharge devices.

4. A method of dosing two types of molding sand into a molding box as defined in claim 1, wherein the feed velocity of both discharge devices are individually regulated.

5. A method of dosing two types of molding sand into a molding box as defined in claim 1, wherein the feed velocity of both discharge devices are conjointly regulated.

6. A method of dosing two types of molding sand into a molding box as defined in claim 1, wherein the step of controlling the movement of said first type of molding sand from said one silo into said intermediate container includes the step of controlling the fall height of the molding sand deposited from at least one of the discharge devices into the intermediate container.

7. A method of dosing at least two types of molding sand into a molding box of a foundry mold situated beneath an intermediate container disposed between respective discharge devices for each type of molding sand, on the one hand, and the molding box, on the other hand, comprising the steps of:

a. carrying out a relative movement between at least'one of the discharge devices and the intermediate container while continuously and progressively depositing a layer of a first type of molding sand received from said at least one discharge device throughout the entire length of the intermediate container, the layer of the first type of molding sand being deposited in the intermediate container with a width substantially corresponding to the width of the intermediate container;

b. controlling the movement of the first type of molding sand during travel from said one discharge device into the intermediate container in order to favorably influence the formation of such first layer of sand within the intermediate container;

c. continuously and progressively depositing a second type of molding sand received from the other of said discharge devices into said intermediate container on top of the previously deposited layer of the first type of molding sand, while maintaining a relative movement between at least one of the discharge devices and the intermediate container, the layer of the second type of molding sand being deposited in said intermediate container with a width substantially corresponding to the width of the intermediate container;

d. aligning the intermediate container provided with the aforementioned two layers of molding sand with the molding box; and

e. then causing the two superimposed layers of molding sand to conjointly and simultaneously fall through said intermediate container into said molding box.

8. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, wherein said second type of molding sand is deposited during a further relative movement between the intermediate container and at least said other of said discharge devices.

9. A methodof dosing at least two types of molding sand into a molding box as defined in claim 7, wherein the two superimpo'sed layers of molding sand in said intermediate container are caused to fall through the bottom of the intermediate container into the molding box.

10. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, including the step of carrying out a substantially linear relative movement between said one discharge device and said intermediate container during depositing of the layer of a first type of molding sand, and carrying out a substantially linear relative movement between the other of said discharge devices and the intermediate con tainer, which is opposite to the first-mentioned linear movement, during depositing of the second type of molding sand into the intermediate container,

ll. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, further including the step of controlling the delivery speed of said discharg devices. r

12. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, wherein the step of controlling the movement of said first type of molding, sand includes the step of controlling the fall height of the molding sand deposited from at least one of said discharge devices into said intermediate container. I i

13. A method for producing foundry molds having a facing sand layer supported by a body of backing sand, using equipment including a supply of facing sand, a supply of backing sand, and means for supporting a mold box below the sand supplies, comprising supporting an intermediate container in a location between the mold box and the sand supplies, the intermediate container having a bottom capable of being closed to support sand in the container and opened to release sand from the container;

continuously releasing facing sand from the facing sand supply and flowing the released facing sand downwardly along an incline into the intermediate container while effecting relative horizontal movement between the incline and the intermediate container,

the step of flowing the released facing sand along the incline being carried out continuously while maintaining the lower end of the incline within the intermediate container and while maintaining the angle of the incline such that the facing 'sand flowing therealong is discharged gently onto the bottom of the intermediate container,

the step of effecting relative horizontal movement between the incline and the intermediate container causing the discharged facing sand to progressively form a continuous essentially uncompacted layer on the bottom of the intermediate container, with the extent of the relative movement and width of the incline being such that said layer completely covers the bottom of the intermediate container;

discontinuing the release and flow of facing sand when the layer offacing sand has been completed; continuously releasing backing sand from the backing sand supply and flowing the released backing sand continuously over a discharge means into the intermediate container while effecting relative horizontal movement between the discharge means and the intermediate container to deposit a layer of backing sand on the layer of facing sand, the discharge means extending horizontally across the line of relative movement and the extent of relative movement being such that the layer of backing sand is deposited progressively over the full extent of the layer of facing sand; discontinuing the release and flow of backing sand when the layer of backing sand has been completed; and openingthe bottom of the intermediate container, while maintaining the same over the mold box, to allow the layers of facing and backing sand to descend into the mold box without undue disruption of the layers.

14. In an apparatus for producing foundry molds comprising two superposed layers each of sand of a different type, the combination of supportmeans for supporting a mold box;

first and second sand supply means located above said support means and each including a discharge device effective, when operated, to continuously release sand from the respective one of said sand supply means;

an intermediate container located above the position occupied by a mold box when the mold box is supported by said support means, said intermediate container having a bottom capable of being closed to retain sand in the container and opened to release sand downwardly therefrom; sand-flow-directing means disposed between said intermediate container and said discharge devices; and

power means for effecting relative horizontal movement between said sand-flow-directing means and said intermediate container in at least one direction while sand is being released by said discharge devices, said sand-flow-directing means including means operative to deposit sand from one of said discharge devices onto the bottom of said intermediate container along a line extending transversely of the direction of such relative horizontal movement and at least substantially over the full width of said intermediate container during such relative horizontal movement, whereby the sand from said one discharge device is caused to progressively form a first sand layer on the bottom of said intermediate container. 15. The combination defined in claim 14, wherein said intermediate container is mounted for horizontal movement relative to said sand-flow-directing means; and said means operative to deposit sand from said one discharge device defines an inclined surface extending downwardly from a point to receive sand released by said one discharge device to a point within said intermediate container. 16. The combination defined in claim 15, wherein said intermediate container comprises two end walls spaced apart in the direction of said relative horizontal movement, one of said end walls extending upwardly for only a relatively short distance from the bottom of said intermediate container, whereby said means defining said inclined surface can enter said intermediate container as said container is moved horizontally relative to said sandflow-directing means, said inclined surface being movable to a vertical position such as to cooperate with said one end wall to retain the deposited sand within said intermediate container. 17. The combination defined in claim 1, wherein said intermediate container is arranged for horizontal movement from a first position aligned above said support means to a second position displaced horizontally therefrom and then back to said first position;

said discharge devices are spaced apart in the direction of said horizontal movement; and said intermediate container comprises two end walls which are spaced apart in the direction of said horizontal movement, said inclined surface being disposed to deposit sand adjacent the one of said end walls nearer said second position when said intermediate container is located at said first position preparatory to movement from said first position to said second position,

a the other of said discharge devices being located near said one discharge device and arranged to release sand from its respective sand supply means toward said surface during horizontal movement of said intermediate container from said second position back to said first position.

18. The combination defined in claim 17, wherein the means defining'said inclined surface is movable to bring said inclined surface into a vertical position at said one end wall when said intermediate container has reached said second position. 19. The combination defined in claim 17, wherein said discharge devices each comprise a horizontal endless conveyor; the means defining said inclined surface is a plate; and said one end wall extends upwardly from the bottom of said intermediate container for only a relatively short distance, whereby said plate can occupy a position slanting from said first discharge device downwardly across the position of said one end wall and into said intermediate container when the latter is in said first position preparatory to deposit of sand therein. 20. The combination defined in claim 15, wherein said intermediate container is arranged for horizontal movement from a first position aligned above said support means to a second position displaced horizontally therefrom and then back to said first position; said discharge devices are spaced apart in the direction of said horizontal movement; and

said sand-flow-directing means comprises means defining a second surface, said second surface being generally upright, located between said inclined surface and the other of said discharge devices, and disposed to direct said sand from said other discharge device into said intermediate container, whereby sand from both of said discharge devices can be deposited in said intermediate container substantially simultaneously, while said container travels from said second position back to said first position, with said second surface directing sand from said other discharge device onto the sand already deposited from said inclined surface.

21. A method for dosing two different types of molding sand into a molding box of a foundry mold using two sand silos and an intermediate container for preparing sand to be filled into the mold box, comprising discharging a first type of sand from one of the silos and directing the discharged sand onto the bottom of the intermediate container along a limited area extending across the intermediate container, while effecting relative horizontal movement between the intermediate container and said limited area in a direction transverse to the limited area, and thereby progressively depositing a layer of said first type of sand on the bottom of the intermediate container; depositing a second type of sand from the other of the silos and directing the discharged sand onto the deposited layer of said first type of sand to provide an overlying layer of said second type of sand; and then conjointly and simultaneously releasing the superimposed layers of said sand from the intermediate container into the mold box. 

1. In a method of dosing two different types of molding sand into a molding box of a foundry mold while using two sand silos with associated discharge devices and an intermediate container, the floor of which is formed by a shutter closure mechanism, said intermediate container being arranged beneath said discharge devices, and with a filling frame which can be placed upon the molding box arranged beneath the intermediate container, the improvement comprising carrying out a relative movement between the discharge devices and the intermediate container while continuously depositing a layer of a first type of molding sand delivered from one of said sand silos until, by reason of said relative movement, said first type of molding sand has been deposited throughout the entire length of the intermediate container and with a width substantially corresponding to the width of the intermediate container, controlling the movement of said first type of molding sand from said one silo into said intermediate container to influence the formation of said first layer of sand within said intermediate container, depositing a second layer of molding sand received from the second sand silo continuously onto and over the entire length of the first layer of molding sand and with a width which substantially corresponds to that of the intermediate container while carrying out a relative movement between the discharge devices and the intermediate container, then bringing the intermediate container into overlying relationship with respect to the filling frame which has been placed upon the molding box, thereafter opening the shutter closure mechanism of the intermediate container, and thereby conjointly and simultaneously depositing both said first and second layers of molding sand from said intermediate container into the molding box.
 2. A method of dosing two types of molding sand into a molding box as defined in claim 1, including the steps of displacing in a first at least approximately linear direction of displacement the intermediate container and the discharge devices relative to one anotheR during removal of molding sand from said one silo, and during removal of molding sand from the second silo carrying out a relative movement between the intermediate container and the discharge devices in a substantially linear direction which is opposite to the first direction of displacement.
 3. A method of dosing two types of molding sand into a molding box as defined in claim 1, further including the step of regulating the feed velocity of both discharge devices.
 4. A method of dosing two types of molding sand into a molding box as defined in claim 1, wherein the feed velocity of both discharge devices are individually regulated.
 5. A method of dosing two types of molding sand into a molding box as defined in claim 1, wherein the feed velocity of both discharge devices are conjointly regulated.
 6. A method of dosing two types of molding sand into a molding box as defined in claim 1, wherein the step of controlling the movement of said first type of molding sand from said one silo into said intermediate container includes the step of controlling the fall height of the molding sand deposited from at least one of the discharge devices into the intermediate container.
 7. A method of dosing at least two types of molding sand into a molding box of a foundry mold situated beneath an intermediate container disposed between respective discharge devices for each type of molding sand, on the one hand, and the molding box, on the other hand, comprising the steps of: a. carrying out a relative movement between at least one of the discharge devices and the intermediate container while continuously and progressively depositing a layer of a first type of molding sand received from said at least one discharge device throughout the entire length of the intermediate container, the layer of the first type of molding sand being deposited in the intermediate container with a width substantially corresponding to the width of the intermediate container; b. controlling the movement of the first type of molding sand during travel from said one discharge device into the intermediate container in order to favorably influence the formation of such first layer of sand within the intermediate container; c. continuously and progressively depositing a second type of molding sand received from the other of said discharge devices into said intermediate container on top of the previously deposited layer of the first type of molding sand, while maintaining a relative movement between at least one of the discharge devices and the intermediate container, the layer of the second type of molding sand being deposited in said intermediate container with a width substantially corresponding to the width of the intermediate container; d. aligning the intermediate container provided with the aforementioned two layers of molding sand with the molding box; and e. then causing the two superimposed layers of molding sand to conjointly and simultaneously fall through said intermediate container into said molding box.
 8. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, wherein said second type of molding sand is deposited during a further relative movement between the intermediate container and at least said other of said discharge devices.
 9. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, wherein the two superimposed layers of molding sand in said intermediate container are caused to fall through the bottom of the intermediate container into the molding box.
 10. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, including the step of carrying out a substantially linear relative movement between said one discharge device and said intermediate container during depositing of the layer of a first type of molding sand, and carrying out a substantially linear relative movement between the other of said discharge devices and the interMediate container, which is opposite to the first-mentioned linear movement, during depositing of the second type of molding sand into the intermediate container.
 11. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, further including the step of controlling the delivery speed of said discharge devices.
 12. A method of dosing at least two types of molding sand into a molding box as defined in claim 7, wherein the step of controlling the movement of said first type of molding sand includes the step of controlling the fall height of the molding sand deposited from at least one of said discharge devices into said intermediate container.
 13. A method for producing foundry molds having a facing sand layer supported by a body of backing sand, using equipment including a supply of facing sand, a supply of backing sand, and means for supporting a mold box below the sand supplies, comprising supporting an intermediate container in a location between the mold box and the sand supplies, the intermediate container having a bottom capable of being closed to support sand in the container and opened to release sand from the container; continuously releasing facing sand from the facing sand supply and flowing the released facing sand downwardly along an incline into the intermediate container while effecting relative horizontal movement between the incline and the intermediate container, the step of flowing the released facing sand along the incline being carried out continuously while maintaining the lower end of the incline within the intermediate container and while maintaining the angle of the incline such that the facing sand flowing therealong is discharged gently onto the bottom of the intermediate container, the step of effecting relative horizontal movement between the incline and the intermediate container causing the discharged facing sand to progressively form a continuous essentially uncompacted layer on the bottom of the intermediate container, with the extent of the relative movement and width of the incline being such that said layer completely covers the bottom of the intermediate container; discontinuing the release and flow of facing sand when the layer of facing sand has been completed; continuously releasing backing sand from the backing sand supply and flowing the released backing sand continuously over a discharge means into the intermediate container while effecting relative horizontal movement between the discharge means and the intermediate container to deposit a layer of backing sand on the layer of facing sand, the discharge means extending horizontally across the line of relative movement and the extent of relative movement being such that the layer of backing sand is deposited progressively over the full extent of the layer of facing sand; discontinuing the release and flow of backing sand when the layer of backing sand has been completed; and opening the bottom of the intermediate container, while maintaining the same over the mold box, to allow the layers of facing and backing sand to descend into the mold box without undue disruption of the layers.
 14. In an apparatus for producing foundry molds comprising two superposed layers each of sand of a different type, the combination of support means for supporting a mold box; first and second sand supply means located above said support means and each including a discharge device effective, when operated, to continuously release sand from the respective one of said sand supply means; an intermediate container located above the position occupied by a mold box when the mold box is supported by said support means, said intermediate container having a bottom capable of being closed to retain sand in the container and opened to release sand downwardly therefrom; sand-flow-directing means disposed between said intermediate container and said discharge devices; and power means for efFecting relative horizontal movement between said sand-flow-directing means and said intermediate container in at least one direction while sand is being released by said discharge devices, said sand-flow-directing means including means operative to deposit sand from one of said discharge devices onto the bottom of said intermediate container along a line extending transversely of the direction of such relative horizontal movement and at least substantially over the full width of said intermediate container during such relative horizontal movement, whereby the sand from said one discharge device is caused to progressively form a first sand layer on the bottom of said intermediate container.
 15. The combination defined in claim 14, wherein said intermediate container is mounted for horizontal movement relative to said sand-flow-directing means; and said means operative to deposit sand from said one discharge device defines an inclined surface extending downwardly from a point to receive sand released by said one discharge device to a point within said intermediate container.
 16. The combination defined in claim 15, wherein said intermediate container comprises two end walls spaced apart in the direction of said relative horizontal movement, one of said end walls extending upwardly for only a relatively short distance from the bottom of said intermediate container, whereby said means defining said inclined surface can enter said intermediate container as said container is moved horizontally relative to said sand-flow-directing means, said inclined surface being movable to a vertical position such as to cooperate with said one end wall to retain the deposited sand within said intermediate container.
 17. The combination defined in claim 1, wherein said intermediate container is arranged for horizontal movement from a first position aligned above said support means to a second position displaced horizontally therefrom and then back to said first position; said discharge devices are spaced apart in the direction of said horizontal movement; and said intermediate container comprises two end walls which are spaced apart in the direction of said horizontal movement, said inclined surface being disposed to deposit sand adjacent the one of said end walls nearer said second position when said intermediate container is located at said first position preparatory to movement from said first position to said second position, the other of said discharge devices being located near said one discharge device and arranged to release sand from its respective sand supply means toward said surface during horizontal movement of said intermediate container from said second position back to said first position.
 18. The combination defined in claim 17, wherein the means defining said inclined surface is movable to bring said inclined surface into a vertical position at said one end wall when said intermediate container has reached said second position.
 19. The combination defined in claim 17, wherein said discharge devices each comprise a horizontal endless conveyor; the means defining said inclined surface is a plate; and said one end wall extends upwardly from the bottom of said intermediate container for only a relatively short distance, whereby said plate can occupy a position slanting from said first discharge device downwardly across the position of said one end wall and into said intermediate container when the latter is in said first position preparatory to deposit of sand therein.
 20. The combination defined in claim 15, wherein said intermediate container is arranged for horizontal movement from a first position aligned above said support means to a second position displaced horizontally therefrom and then back to said first position; said discharge devices are spaced apart in the direction of said horizontal movement; and said sand-flow-directing means comprises means defining a second surfAce, said second surface being generally upright, located between said inclined surface and the other of said discharge devices, and disposed to direct said sand from said other discharge device into said intermediate container, whereby sand from both of said discharge devices can be deposited in said intermediate container substantially simultaneously, while said container travels from said second position back to said first position, with said second surface directing sand from said other discharge device onto the sand already deposited from said inclined surface.
 21. A method for dosing two different types of molding sand into a molding box of a foundry mold using two sand silos and an intermediate container for preparing sand to be filled into the mold box, comprising discharging a first type of sand from one of the silos and directing the discharged sand onto the bottom of the intermediate container along a limited area extending across the intermediate container, while effecting relative horizontal movement between the intermediate container and said limited area in a direction transverse to the limited area, and thereby progressively depositing a layer of said first type of sand on the bottom of the intermediate container; depositing a second type of sand from the other of the silos and directing the discharged sand onto the deposited layer of said first type of sand to provide an overlying layer of said second type of sand; and then conjointly and simultaneously releasing the superimposed layers of said sand from the intermediate container into the mold box. 